Platform as a Service to handle tens of thousands of simultaneous long term network connections

Question

Is there a Platform as a Service (PaaS, e.g. Google App Engine or Windows Azure) that for a reasonable cost can be used to run a server for relaying peer to peer "real time" communication between clients?

This system will in my case be used to relay (small amounts of) network traffic to and from small home automation gadgets with limited resources programmed in embedded C, to Android and iOS apps. In a few years I expect several tens of thousands of simultaneous connections.

The reason I am looking for a PaaS solution and not IaaS is that I would like to minimize the time and expertise needed for virtual computer, OS and server application maintenance.

Because of the resource constraints of the home automation gadget, a solution like PubNub is not possible. I have a few thousand bytes of available program flash for my embedded C code, so the protocol used would have to be pretty basic (e.g. raw TCP or UDP, HTTP or WebSockets).

Using "long polling" with Google App Engine (GAE) would be too expensive, as they bill for the whole duration of the connection even if almost no traffic is transfered. GAE supports Sockets, but only outgoing sockets and not listening sockets on the server. Is it possible to get around this limitation somehow by e.g. sending a UDP packet to GAE first (to punch a hole in the user's firewall, and having GAE then initiating an outgoing socket back to the home automation gadget or Android/iOS app?

Or do you see any other possible solutions using the PaaS aspects of Windows Azure or other PaaS providers?

Any tips or possible solutions are greatly appreciated!

Answer 1

AMQP seems like it would fit your protocol needs and the Apache Qpid/Proton project has some client libraries, their C code might meet your needs. On the service side you could test things out using Azure ServiceBus since it speaks AMQP. If that didn't meet your needs you could host a worker role and run one of the AMQP clients in there.

Another option to consider is ZeroMQ. They have a lot of very simple client APIs and building a relay service that ran in a Worker role would be a trivial amount of code. Java Sample C# Sample Those samples are using an "inproc" transport and I'm guessing you want to switch that to TCP.